Knobs are well known for rotating the shafts of switches and the like. Such knobs generally mount to the shafts of switches in one of two manners. The knob can simply slide over the shaft and be held in position by a key formed in the knob which engages a keyway formed in the shaft. Alternatively a set screw on the knob can be used to secure the knob the shaft.
When a keyed knob is used on a shaft which is formed to receive the keyed knob, the knob is pushed completely onto the shaft and no provision is made for axial positioning of the knob on the shaft. Axial adjustment of the knob along the length of the switch shaft is desirable so that the knob can be used with shafts of varying lengths and with various thicknesses of faceplates which are used to cover switch assemblies.
When a knob having a set screw is attached to a shaft, the knob can be positioned axially along the length of the shaft prior to tightening the set screw, which secures the knob to the shaft. Therefore, knobs secured with set screws may be axially positioned upon the shaft. When a knob with a set screw is used the set screw must be accessible through the knob so that it can be tightened to secure the knob to the shaft and loosened to remove the knob from the shaft. The set screw is disposed in a threaded aperture in the knob. This aperture extends from the outer periphery of the knob through the knob to the inner opening of the knob into which the shaft is received. Therefore, the aperture and set screw are visible on the periphery of the knob. That is, the set screw and the aperture can be seen by the user when using the knob to rotate the shaft of the switch. Visibility of the set screw and aperture on the periphery of the knob detracts from the aesthetic appeal of the knob. Knobs intended for use in fashionable home and commercial settings are intended to be aesthetically pleasing as well as functional. Therefore, the visibility of any mounting hardware is to be minimized.
Fashionable knobs, having no set screw or threaded aperture, are commonly used in the prior art. This is accomplished by using knobs of the keyed central opening type. However, such knobs are not axially positionable and cannot be used in all applications. Therefore, when a knob must be used that is axially positionable, then a knob must be chosen which has a visible set screw and threaded aperture.
As such the prior art has recognized the problem of providing knobs having a pleasing appearance and also the problem of providing knobs which are axially positionable upon the shaft of a switch. However, the proposed solutions have to date been ineffective in providing a satisfactory remedy.